Carburetor step-up control



June 11, 1940. L, BOYCE 2,204,527

1 CARBURETOR STEP-UP CONTROL Filed Feb. 7, 1939 \r :3: 28 5' Z6 24 a Zdr 22 j' 27 I x 5 17 12 l l 7 10 20 11 z 14 3 :I: g 3-- 24$ 71 U u FIG 2 E i '15 I? y g v f 15 a .a 20

INVENTOR 7 1? LEONARD D. BOYCE AT TO RN EY Patented June 11, 1940 s i '1 1 UNITED STATES PATENT OFFICE CARBURETOR STEP-U1 CONTROL Leonard D. Boyce, Maplewood, Mo., assignor to Carter Carburetor Corporation, St. LouiS,.Mo., a, corporation of Delaware Application February 7, 1939, Serial No. 255,154

' z ciaims. (01. 261-459) This inventionv relates. to carburetors for internal combustion engines and particularly to so-called step-up mechanisms therefor.

Most automotive carburetors now in use are provided with means for enriching the mixture supplied when the associated engine is subjected to an extra heavy load. Such means may take the form of a device responsive to suction posterior to the throttle for opening an auxiliary metering jet or for enlarging the effective area of the main metering jet, or the device may be operated mechanically from. the throttle valve. The step-up device is ordinarily necessary only under extreme load conditions, and during most driving, an automobile engine will function to the satisfaction of the driver without this auxiliary fuel. Obviously, operation of the step-up device affects the economical operation of. the

vehicle.

Accordingly, it is an object of this invention to provide thermostatic means for restricting or preventing the operation of the step-up device under relatively high temperature conditions.

This object and other more detailed objects hereafter appearing are attained substantially by the device illustrated in the accompanying drawing, in which:

Fig. 1 is a vertical transverse section illustrating a carburetor embodying the invention.

Fig. 2 is a view of a portion of the structure shown in Fig. 1, but with parts in different operative positions.

The carburetor shown includes an air horn I, venturis 2, and outlet portion 3 forminga mixture conduit, the outlet portion being flanged as at 4 for attachment to the intake manifold (not shown) of an associated internal combustion the throat of the upper venturi 2.

There is also provided a suction step-up device including an additional orifice member I2] opening into the main nozzle passage and controlled by a needle l3 extending through a guide [4 and yieldingly secured at its upper end through coiled spring l5 to a strap Hi. Adjacent needle I3 is a cylinder 5? communicating through passage l8 with the carburetor mixture conduit posterior to throttle .5. A piston I9 is slidable in cylinder I1 and constantly urged upwardly by coiled spring 2i]. Strap I6 is secured to piston 19 whereby needle 13 reciprocates vertically with the piston responsive to suction conditions in the mixture 5 conduit. The various parts are constructed so that when the engine intake suction drops below a predetermined value, on the order of two inches of mercury, spring 20 will force piston I9 and needle l3 upwardly, opening auxiliary orifice member IE to supply additional fuel to the mixture conduit. V

A reach pin 2| is slidable in an apertured boss or bearing 22, carried in a recessed portion 23 of the float bowl cover and, at its upper end, is 5 connected by a link 24 to one arm of a bell crank 25, pivotally mounted at 26 on a bracket 21 projecting above the bowl cover. A Bowden wire 28 is secured to the other arm of hell crank 25 and preferably extends to, the dash-board of the) vehicle or another point convenient to the operator from the drivers seat. This mechanism is arranged so that when Bowden wire 28 is pushed inwardly, reach pin 2| is moved downwardly against suction piston I9 so as to limit or prevent 5 upward movement thereof under the influence of spring in and, consequently, limit or prevent opening of the step-up orifice. Thus the step-up device may be manually controlled at the option of the driver. When wire 28 is pulled outwardly, or to the left, sufiicient space is provided between pin 2| and piston l9, as shown in Fig. 2, topermit normal operation of the step-up.

The invention is intended for use with any sort of step-up device having a member yieldably movable with the step-up needle or valve. The form of the manual control and also various features of the carburetor are not essential and these may be modified as will occur to those skilled in the art. The exclusive use of all modi- 40 fications as come within the scope of the appended claims is contemplated.

I claim:

1. In combination with an internal combustion engine intake conduit, a carburetor for association with said intake conduit includinga manually actuated throttle, a float bowl and a cover therefor, a main fuel passage for admitting fuel from said bowl to said conduit during normal operation of the engine, an auxiliary fuel passage opening into the main fuel passage for enriching the mixture in said conduit, a valve associated with said'auxiliary fuel supply passage, suction responsive means including a piston for normally actuating said valve in response to suction variations in said-conduit to automatically enrich the mixture in said conduit when the pressure in the intake passage decreases to a predetermined value, a guide member supported by the cover of the float bowl, a slidable element in said guideway for engagement with said piston, and manually actuated means supported by the carburetor for causing the slidable member to engage said piston to cause the latter to positively move said valve to closed position whereby the normal suction actuation of said valve is prevented and the fuel supply to, said conduit "is limited to the main fuel passage.

2. In combination with an internal combustion engine intake conduit, a carburetor for association with said intake conduit including a manually actuated throttle, a float bowl and a cover therefor, a main fuel passage for admitting fuel from said bowl to said conduit during normal operation of the engine, an auxiliary fuel passage opening into the main fuel passage for enriching the mixture in said conduit, a valve associated with said auxiliary fuel supply passage, suction responsive means including a piston for normally actuating said valve in response to suction variations in said conduit to automatically enrich the mixture in said conduit when the pressure in the intake passage decreases to a predeter- I said pin, and manual means for moving said bell crank on its pivot to cause said reach pin to move said valve to closed position, whereby the movement of said fuel supply to said conduit is limited to the capacity of the main fuel passage and normal suction actuation of said valve is 20 prevented.

LEONARD D. BOYCE. 

